Chagas' disease remains a serious public health problem in Central and South America and considerable research is required to understand the nature of intracellular parasitism exemplified by this disease. Of particular importance is the mode of entry of the parasites into the host cells and the specific receptors that mediate contact and adherence in the trypanosome-phagocyte interaction. There is growing evidence that these receptors are glycoproteins, which can be identified and isolated through the use of lectins and other probes such as sugar-binding myeloma immunoglobulins. The immediate goal of this project is to identify, isolate and characterize these receptors as fully as possible and then determine their efficacy as vaccines to protect experimental hosts from challenge infections. Most experiments will be carried in a culture system, which we developed recently. The rational for the present proposal is based on our previous findings that indicated (1) unique lectin receptors on the surface of the developmental stages of the trypanosome and (2) strictly stage-specific cell surface substances with carbohydrate recognition sites, namely lectins and glycosidase (neuraminidase). Specific assays and methods involving aspects of cell biology, biochemistry and immunochemistry for most of the proposed studies have already been developed. The results of these studies may not only further our understanding of the basic mechanisms of intracellular parasitism but may also be of value in prevention, therapy and diagnosis of the disease. And it should not be overlooked that these studies may reveal new classes of substances in trypanosome that may have substantial importance for fundamental investigations in cell biology.